A nasogastric tube is a generally flexible tube inserted through a patient's nasal passages to extend through the esophagus and into the stomach, for the purposes of allowing the introduction of fluids into the stomach, the removal of fluids from the stomach, or both. A nasogastric tube is often used in an emergency situation in an emergency room, trauma center, or immediate care facility. The nasogastric tube is usually inserted by or under the supervision of a physician. There are a number of situations in which the use of a nasogastric tube may be indicated, including, without limitation: upper gastrointestinal bleeding; a bowel obstruction or illeus; ingestion of a poison, contaminant, or drug of inappropriate kind or quantity (i.e., an “overdose”); or when whole bowel irrigation is needed.
Known nasogastric tubes are constructed of a generally flexible material and have one or more separate interior bores or lumina, each extending most of the length of the tube. Kim U.S. Pat. No. 3,999,554 discloses an exemplary nasogastric tube. Plural lumina allow multiple functions, such as the introduction of fluids, removal of fluids, and ventilation of the region around the end of the tube, to be performed simultaneously. The construction of known nasogastric tubes varies, but in general, at one end intended for insertion into the patient, openings are provided to allow communication of fluids, possibly including gases, between the interior lumina and the region surrounding the end of the tube. At the opposite end of the nasogastric tube, separate sockets or tubes are provided for connection to various sources of fluids to be introduced into the patents stomach or to suction to remove fluids or gases from the patient's stomach.
Several significant disadvantages manifested by known nasogastric tubes arise during the process of inserting the nasogastric tube through the patient's nasal passages and into the stomach.
One disadvantage of known nasogastric tubes is the difficulty of safely inserting the nasogastric tube so that it does not incorrectly intubate the patient's trachea and lungs. Conventionally, the nasogastric tube is placed into the patient's nostril and pushed into the back of the oropharynx. The tube is typically lubricated at the tip. In some cases, the back of the oropharynx is numbed with a numbing spray. When the tube is in the oropharynx, the patient is asked to swallow the tube. The tube has some rigidity and cannot be independently swallowed by the patient. Instead, the person inserting the tube assists by pushing the tube into the esophagus and into the stomach while the patient is attempting to swallow.
Because the nasogastric tube is flexible and must undergo a significant bend in the oropharynx, it is impossible to precisely control the position of the end of the tube, and there is considerable risk that the tube will enter the trachea and eventually the lung, instead of the esophagus. Intubating the trachea and lung can have severe consequences, including death. Such intubation may cause damage to vocal cords and airway. It also may cause an extreme coughing and gag response in some patients. In some cases, the patient experiences such discomfort that the patient will not thereafter allow any further attempts at placing the nasogastric tube. In other cases, the patient may tolerate the nasogastric tube even after it has entered the lung, and may even be able to speak. This may cause the healthcare provider to erroneously believe the nasogastric tube has been properly placed in the stomach. If the nasogastric tube is incorrectly placed, and medication is improperly introduced into the lungs instead of the stomach, it could cause extreme morbidity or even death.
The epiglottis covers the trachea during the act of swallowing. The risk of intubating the trachea can be minimized by pushing the tube into the esophagus while the patient is attempting to swallow and entrance to the trachea is blocked by the epiglottis. However, this requires precise timing on the part of the medical professional who is inserting the tube. A further problem is that some patients cannot attempt to swallow because the tube activates their gag reflex. Although the tube is generally flexible, it is rigid compared to tissues of the oropharynx and esophagus, and even when a numbing agent has been used, some patients will gag. Because they are unable to swallow, the epiglottis does not cover the trachea and the nasogastric tube may intubate the trachea and lungs.
Another disadvantage of known nasogastric tubes is that pushing the hard tip of the nasogastric tube through the nasal passage and sinus often causes pain, bleeding, and significant trauma to the nasal cavity. The tube may abrade or irritate the tissues it encounters, particularly where it must bend downward toward the esophagus. In addition, the entire process can cause significant discomfort to the patient.
Other workers in this field have sought to remedy some of these disadvantages. Knott U.S. Pat. No. 5,690,620 discloses an anatomically conforming nasogastric tube having a normally-curved or normally-bent leading end and an additional bend near the leading end. The bent portion of the nasogastric tube is intended to conform to the shape of the soft palate, thereby applying a reduced pressure against the posterior nasopharynx. Knott further discloses a method of inserting the nasogastric tube which involves rotating the tube to bias the bent leading end of the tube in various desired directions so as to avoid obstructions, reliably enter the esophagus, or bias the tip in a particular position with respect to the stomach outlet. However, Knott's apparatus and method do not assure that the leading end of the tube will not encounter, abrade, and irritate tissues during insertion. It also does not resolve the problem that the presence of the tube excites the patient's gag reflex. Moreover, rotating the trailing end of the tube does not ensure that the leading edge of the tube will identically rotate. Therefore, the difficulty of precisely positioning the leading end of the nasogastric tube remains. Thus, the Knott nasogastric tube does not satisfactorily resolve the problems of potentially intubating the trachea and lung, irritating or damaging the nasal cavity, and causing patient discomfort.
Peters U.S. Pat. No. 5,391,158 discloses a system for introducing a nasogastric tube into the stomach of a patient. The Peters system includes a digestible weight to be swallowed by the patient, and a digestible guide string having one end attached to the weight. The nasogastric tube is telescoped around the guide string; during the tube's insertion it follows the guide string into the patient's stomach. Peters discloses that the digestible weight is inserted through the patient's nostril to the nasopharynx. However, Peters does not disclose how the weight is propelled to the nasopharynx, and it is believed this presents a significant difficulty in using the device. In addition, in many instances in which a nasogastric tube is needed, the patient's digestive system is not functioning properly. It is dangerous to assume that the “digestible” weight and guide string can actually be digested. The use of a “digestible” weight and string could even aggravate the patient's condition, and may cause other complications. Thus, the Peters nasogastric tube and insertion system also does not satisfactorily resolve the aforementioned disadvantages of known nasogastric tubes.
There has remained a need in the art for a nasogastric tube which can be safely inserted into the patient, which minimizes risk of intubating the trachea and lungs, which avoids damage to the oropharynx, the esophagus, and other tissues, and which minimizes patient discomfort during insertion.